A fluorescent lamp, which is commonly used for a lighting device, is operated at a frequency of 60 Hz, leading to severe eye fatigue due to flickering when it is used for a long period of time.
Further, when the fluorescent lamp is used for a long period of time, it may increase the ambient temperature due to self-heating, and may cause high electric loss.
In contrast, an LED lamp has advantages in that the efficiency of conversion of electric power into light is remarkably high, it produces highly efficient intensity of illumination at low voltage, it has anti-glare properties, and the operational stability is excellent, with the result that an LED lamp has come to be widely used for lighting devices.
A light-emitting module, which includes a plurality of LEDs as a light source, is employed as a lighting device, in which maintenance of uniform luminance is required in order to relieve user eye fatigue.